Data transmission method and apparatus and data receiving method and apparatus

ABSTRACT

When transmitting live information data, a reproduction start waiting time associated with reproduction of the live information data on the receiving side can be reduced. Encoded data is divided in sequence into a plurality of data segments each having a predetermined time length. In this case, the time length of each data segment is increased in sequence for each data segment until a predetermined time length is reached and is fixed to the predetermined time length after the predetermined time length is reached. The plurality of data segments which are formed in a divided manner are converted into a plurality of segmented packet data or a plurality of continuous packet data, and the data is transmitted through individual data transmission channels, thus performing multiple-channel parallel transmission.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a data transmission method andapparatus therefor, for dividing information data, such as on-demandbroadcast signal data, into a plurality of data segments and fortransmitting each of the data segments formed in a divided mannerthrough individual data transmission channels, and to a data receivingmethod and apparatus therefor, for receiving data transmitted by such adata transmission method or apparatus therefor.

2. Description of the Related Art

A method has been proposed in which, in television broadcasts in whichmovies or recorded images/audio are content, content desired on thereceiving side at a desired time can be received. A broadcast in such amethod is called a “broadcast of an on-demand method (on-demandbroadcast)”. With remarkable developments in digital technology in bothareas of hardware and software and heavy diversification of contentwhich is broadcast, the present situation is that such on-demandbroadcasts are expected to become widely used.

In data transmission using the on-demand form such as on-demandbroadcasts, information data representing content to be broadcast ismade to be, for example, encoded data on which a predetermined codingprocess is performed. When performing data processing for thetransmission of the encoded data, for data division, generally, twotechniques are used, and for data transmission, generally, twotechniques are used.

One of the two techniques regarding data division is an equal-lengthdivision technique for dividing encoded data representing various typesof content into a plurality of data segments having an equal timelength. The other technique is an unequal-length division technique fordividing encoded data representing various types of content into aplurality of data segments having a gradually increasing time length.Furthermore, one of the two techniques regarding data transmission is arepeated transmission technique for converting each of a plurality ofdata segments, formed as a result of encoded data representing varioustypes of content being divided, into segmented packet data in order toform a plurality of segmented packet data and for repeatedlytransmitting each of the segmented packet data. The other technique is acontinuous transmission technique for obtaining continuous packet databy performing specific coding on each of a plurality of data segments,formed as a result of encoded data representing various types of contentbeing divided, in order to form a plurality of continuous packet dataand for continuously transmitting each of the continuous packet data.

FIG. 12 is a timing chart which conceptually shows an example of datatransmission of an on-demand form in which an equal-length divisiontechnique and a repeated transmission technique are used. In thisexample, encoded data representing predetermined content to betransmitted is divided into p data segments DS1 to DSp having an equaltime length.

The data segment DS1 which is formed in a divided manner is convertedinto segmented packet data DP1. The segmented packet data DP1 is formedas packet stream data on which a predetermined coding process isperformed. Then, the segmented packet data DP1 is repeatedly transmittedthrough a data transmission channel CH1.

In a similar manner, the data segments DS2 to DSp which are formed in adivided manner are converted into segmented packet data DP2 to DPp whichis packet stream data, respectively, on which a predetermined codingprocess is performed. Then, the segmented packet data DP2 to DPp isrepeatedly transmitted through data transmission channels CH2 to CHp,respectively.

In this manner, the segmented packet data DP1 to DPp which is repeatedlytransmitted through individual data transmission channels (each of thedata transmission channels CH1 to CHp) forms transmission data of pchannels. On the receiving side, at any desired time, the segmentedpacket data DP1 to DPp sent as transmission data of p channels arereceived in sequence, the data segments DS1 to DSp which are based onthe received segmented packet data DP1 to DPp, respectively, areobtained, these data segments are sent in sequence, and the encoded datarepresenting the original content is reproduced.

FIG. 13 is a timing chart which conceptually shows an example of datatransmission of an on-demand form in which an equal-length divisiontechnique and a continuous transmission technique are used. Also in thisexample, encoded data representing predetermined content to betransmitted is divided into p data segments DS1 to DSp having an equaltime length.

As a result of a specific coding process being performed on the datasegment DS1 which is formed in a divided manner, the data segment DS1 isconverted into continuous packet data DLT1 which is composed of acontinuous packet stream. For a specific coding process in such a case,a special coding process (hereinafter referred to as an “LT codingprocess”) is used in which, for example, a packet stream with nearlyinfinite continuousness is formed so as to be capable of reproducing theoriginal data segment DS1 from, for example, one of the portions havingthe amount of data corresponding to approximately 105% of the datasegment DS1 (portion of a predetermined amount of data) within thatpacket stream. Then, the continuous packet data DLT1 is continuouslytransmitted through the data transmission channel CH1.

In a similar manner, as a result of, for example, a specific codingprocess, which is an LT coding process, being performed on each of thedata segments DS2 to DSp which are formed in a divided manner, the datasegments DS2 to DSp are converted into continuous packet data DLT2 toDLTp, each of which is composed of a continuous packet stream. Then, thecontinuous packet data DLT2 to DLTp is continuously transmitted throughdata transmission channels CH2 to CHp, respectively.

In this manner, the continuous packet data DLT1 to DLTp which istransmitted through individual data transmission channels (each of thedata transmission channels CH1 to CHp) forms transmission data of pchannels. On the receiving side, at any desired time, a portion of apredetermined amount of data in each of the continuous packet data DLT1to DLTp, sent as transmission data of p channels, is received insequence, the data segments DS1 to DSp based on the portion of apredetermined amount of data in each of the received continuous packetdata DLT1 to DLTp, respectively, are obtained, these data segments aresent in sequence, and the encoded data representing the original contentis reproduced.

FIG. 14 is a timing chart which conceptually shows an example of datatransmission of an on-demand form in which an unequal-length divisiontechnique and a repeated transmission technique are used. In thisexample, encoded data representing predetermined content to betransmitted is divided into q data segments DS1 to DSq having agradually increasing time length.

The data segment DS1 which is formed in a divided manner so as to havethe shortest time length is converted into segmented packet data DP1.The segmented packet data DP1 is formed as packet stream data on which apredetermined coding process is performed. Then, the segmented packetdata DP1 is repeatedly transmitted through the data transmission channelCH1.

The data segments DS2 to DSq which are formed in a divided manner so asto be longer than the time length of the data segment DS1 and so as tohave gradually increasing time lengths are also converted into segmentedpacket data DP2 to DPq, which is formed as packet stream data on which apredetermined coding process is performed, respectively. Then, thesegmented packet data DP2 to DPq is repeatedly transmitted through datatransmission channels CH2 to CHq, respectively.

In this manner, the segmented packet data DP1 to DPq which is repeatedlytransmitted through individual data transmission channels (each of thedata transmission channels CH1 to CHp) forms transmission data of qchannels. On the receiving side, at any desired time, the segmentedpacket data DP1 to DPq sent as transmission data of q channels isreceived in sequence, the data segments DS1 to DSq which are based onthe received segmented packet data DP1 to DPq, respectively, areobtained, these data segments are sent in sequence, and the encoded datarepresenting the original content is reproduced.

FIG. 15 is a timing chart which conceptually shows an example of datatransmission of an on-demand form in which an unequal-length divisiontechnique and a continuous transmission technique are used. Also in thisexample, encoded data representing predetermined content to betransmitted is divided into q data segments DS1 to DSq having agradually increasing time length.

The data segment DS1 which is formed in a divided manner so as to havethe shortest time length is converted into continuous packet data DLT1composed of a continuous packet stream, for example, as a result of aspecific coding process which is an LT coding process being performedthereon. Then, the continuous packet data DLT1 is continuouslytransmitted through the data transmission channel CH1.

In a similar manner, the data segments DS2 to DSq which are formed in adivided manner so as to be longer than the time length of the datasegment DS1 and so as to have a gradually increasing time length arealso converted into continuous packet data DLT2 to DLTq, each of whichis composed of a continuous packet stream, as a result of a specificcoding process which is an LT coding process being performed on each ofthe data segments. Then, the continuous packet data DLT2 to DLTQ iscontinuously transmitted through the data transmission channels CH2 toCHq, respectively.

In this manner, the continuous packet data DLT1 to DLTq which istransmitted through individual data transmission channels (each of thedata transmission channels CH1 to CHq) forms transmission data of qchannels. On the receiving side, at any desired time, the portion of apredetermined amount of data in each of the continuous packet data DLT1to DLTQ sent as transmission data of q channels is received in sequence,the data segments DS1 to DSq which are based on the portion of thepredetermined amount of data in each of the received continuous packetdata DLT1 to DLTq, respectively, are obtained, these data segments aresent in sequence, and the encoded data representing the original contentis reproduced.

In either case of the data transmission of the on-demand form using anequal-length division technique, such as an example of which is shown inFIGS. 12 and 13 and the data transmission of the on-demand form using anunequal-length division technique, such as an example of which is shownin FIGS. 14 and 15, on the receiving side, reproduction of the datasegment DS1 is performed after the reception of the portion of thepredetermined amount of data in the segmented packet data DP1 or thecontinuous packet data DLT1 is completed. In a similar manner, thereproduction of each of the data segments DS2 to DSp or the datasegments DS2 to DSq is also performed after the reception of the portionof the predetermined amount of data in the continuous packet data DLT2to DLTp or in the continuous packet data DLT2 to DLTq is completed.Therefore, on the receiving side, when the reception of thepredetermined amount of data in the segmented packet data DP1 or thecontinuous packet data DLT1 is completed, the reproduction of the datasegments DS1 to DSp or the data segments DS1 to DSq is started, and inorder to make the reproduction start waiting time for the data segmentsDS1 to DSp or the data segments DS1 to DSq short, the time length of thedata segment DS1 is made relatively short.

Therefore, in the case of the data transmission of the on-demand formusing the equal-length division technique, each of the data segments DS1to DSp is made to have a relatively short time length. As a result, thenumber of data divisions for the encoded data representing the contentto be transmitted becomes relatively large, and the number of datatransmission channels becomes relatively large.

In contrast, in the case of the data transmission of the on-demand formusing the unequal-length division technique, the time length of the datasegment DS1 is made to be relatively short, but the time length of eachof the data segments DS2 to DSq is gradually increased. As a result, thenumber of data divisions for the encoded data representing content to betransmitted is less than that in the case of the data transmission ofthe on-demand form using the equal-length division technique, and alesser number of data transmission channels is required. Therefore, fromthe viewpoint of reducing the number of data transmission channels, datatransmission of the on-demand form using the unequal-length divisiontechnique is desirable.

In such a situation, in the data transmission of the on-demand form,when content to be transmitted is so-called live information, such aslive performance information, live program information, live broadcastinformation, etc., on the receiving side, after the start time of thelive information (the start time of a live performance, a live program,a live broadcast, etc.), a reproduction start waiting time up to thetime encoded data representing content which is that live information(live content) can be reproduced from the beginning occurs.

FIG. 16 is a timing chart showing an example of data transmission of anon-demand form in which content to be transmitted is live information.In this example, an unequal-length division technique is used to reducethe number of data transmission channels, and a repeated transmissiontechnique is used.

In the case of such an example shown in FIG. 16, encoded datarepresenting live content is divided into r data segments DS1 to DSrhaving a gradually increasing time length. At a live information starttime t1, encoded data representing live content begins to be formed, andrepeated transmission of the segmented packet data DP1 based on the datasegment DS1, through the data transmission channel CH1, is started.Thereafter, repeated transmission of the segmented packet data DP2 toDPr based on the data segments DS2 to DSr, through the data transmissionchannels CH2 to CHr, respectively, is started in sequence.

On the receiving side, at time t4 when the reception of data whicharrives first within the segmented packet data DPr which is repeatedlytransmitted through the data transmission channel CHr, is completed, thereproduction of the data segment DSr based on the received segmentedpacket data DPr can be started. Therefore, time t2 obtained bycalculating backwards, from time t4, the corresponding time lengths ofthe data segments DSr−1 to DS1 reproduced before time t4, is assumed tobe a time when the reproduction of the data segment DS1 based on thesegmented packet data DP1 is started, and after the reproduction of thedata segment DS1, the reproduction of the data segments DS2 to DSr basedon the segmented packet data DP2 to DPr is performed in sequence. Thatis, from time t2, the data segments DS1 to DSr can be reproducedcontinuously from the beginning.

In such a situation, a reproduction start waiting time Tv from the liveinformation start time t1 to the time t2 occurs. For a person whoreproduces the data segments DS1 to DSr on the reproduction side, it ispreferable that such a reproduction start waiting time Tv be as short aspossible.

The time t4, which is a reference for determining the reproduction startwaiting time Tv, is a time when the encoded data representing livecontent ends. Therefore, the reproduction start waiting time Tv fromtime t1 to time t2 is made to be equal to the time length of the datasegment DSr, which begins to be reproduced at time t4. The data segmentDSr is a segment with the maximum time length among the data segmentsDS1 to DSr. Therefore, the reproduction start waiting time Tv from timet1 to time t2 becomes a relatively long time, and the condition suchthat the reproduction start waiting time is preferably as short aspossible for a person who reproduces the data segments DS1 to DSr cannotbe satisfied.

FIG. 17 is a timing chart showing another example of data transmissionof an on-demand form in which content to be transmitted is liveinformation. In this example, an unequal-length division technique isused to reduce the number of data transmission channels, and acontinuous transmission technique is used.

Also in the case of such an example as shown in FIG. 17, encoded datarepresenting live content is divided into r data segments DS1 to DSrhaving a gradually increasing time length. At a live information starttime t5, encoded data representing live content begins to be formed, andwhen the formation of the data segment DS1 is completed after the liveinformation start time t5, the transmission of the continuous packetdata DLT1 based on the data segment DS1, through the data transmissionchannel CH1, is started. Thereafter, when the formation of each of thedata segments DS2 to DSr is completed, transmission of the continuouspacket data DLT2 to DLTr based on the data segments DS2 to DSr, throughthe data transmission channels CH2 to CHr, respectively, is started insequence.

On the receiving side, at a time t8 when the reception of the portion ofthe predetermined amount of data of the continuous packet data DLTr,which is obtained first, which is transmitted through the datatransmission channel CHr, the reproduction of the data segment DSr basedon the portion of the predetermined amount of data in the receivedcontinuous packet data DLTr can be started. Therefore, a time t6, whichis obtained by calculating backwards, from time t8, each of the timelengths of the data segments DSr−1 to DS1 reproduced before time t8, isassumed to be a time when the reproduction of the data segment DS1 basedon the portion of the predetermined amount of data in the continuouspacket data DLT1 is started, and after the reproduction of the datasegment DS1, the reproduction of the data segments DS2 to DSr based onthe portion of the predetermined amount of data in each of thecontinuous packet data DLT2 to DLTr is performed in sequence. That is,from time t6, the data segments DS1 to DSr can be reproducedcontinuously from the beginning.

In such a situation, a reproduction start waiting time Tw from the liveinformation start time t5 to time t6 occurs. Of course, for a person whoreproduces the data segments DS1 to DSr on the reproduction side, such areproduction start waiting time Tw is a time which is preferably asshort as possible.

The time t8 which is a reference for determining the reproduction startwaiting time Tw is a time such that a time corresponding to the timelength of the portion of the predetermined amount of data of thecontinuous packet data DLTr, which is obtained first, has passed fromthe time t7 when the encoded data representing live content ends.Therefore, the reproduction start waiting time Tw from time t5 to timet6 is made to be equal to the sum of the time length of the portion ofthe predetermined amount of data, which is obtained first, of thecontinuous packet data DLTr which is begun to be sent at time t7 and thetime length of the data segment DSr whose reproduction is started attime t8. The data segment DSr is a segment that has the maximum timelength among the data segments DS1 to DSr. Therefore, the reproductionstart waiting time Tw from time t5 to time t6 becomes a relatively longtime, and the condition such that the reproduction start waiting time beas short as possible for the person who reproduces the data segments DS1to DSr cannot be satisfied.

SUMMARY OF THE INVENTION

In view of such points, an object of the present invention is to providea data transmission method and apparatus therefor, which are capable ofreducing a reproduction start waiting time associated with thereproduction of information data (live information data) on thereceiving side, for example, when content to be transmitted is livecontent in a case where data transmission of an on-demand form using theunequal-length division technique with regard to information datarepresenting predetermined content to be transmitted, is to beperformed, and to provide a data receiving method and apparatustherefor, for receiving data transmitted by such a data transmissionmethod and apparatus therefor.

To achieve the above-mentioned object, in one aspect, the presentinvention provides a data transmission method comprising the steps of:dividing information data in sequence into a plurality of data segments,each having a predetermined time length, in such a manner that thepredetermined time length of each data segment is increased in sequencefor each of the data segments until a predetermined time length isreached, and that, after the predetermined time length is reached, thelength is fixed to the predetermined time length; converting each of theplurality of data segments which are formed in a divided manner intosegmented packet data in order to form a plurality of segmented packetdata; and repeatedly transmitting each of the plurality of segmentedpacket data through individual data transmission channels, thusperforming multiple-channel parallel transmission.

In another aspect, the present invention provides a data transmissionmethod comprising the steps of: dividing information data in sequenceinto a plurality of data segments, each having a predetermined timelength, in such a manner that the predetermined time length of each datasegment is increased in sequence for each of the data segments until apredetermined time length is reached, and that, after the predeterminedtime length is reached, the length is fixed to the predetermined timelength; obtaining continuous packet data by performing a specific codingprocess on each of the plurality of data segments which are formed in adivided manner in order to form a plurality of continuous packet data;and repeatedly transmitting each of the plurality of continuous packetdata through individual data transmission channels, thus performingmultiple-channel parallel transmission.

In another aspect, the present invention provides a data transmissionapparatus comprising: information data entering means for enteringinformation data to memory means; data dividing means for dividing theinformation data entered into the memory means in sequence into aplurality of data segments, each having a predetermined time length, insuch a manner that the predetermined time length is increased insequence for each of the data segments until a predetermined time lengthis reached, and that, after the predetermined time length is reached,the length is fixed to the predetermined time length; packet dataforming means for converting each of the plurality of data segmentswhich are formed in a divided manner by the data dividing means intosegmented packet data in order to obtain a plurality of segmented packetdata; and data transmission means for repeatedly transmitting each ofthe plurality of segmented packet data obtained by the packet dataforming means through individual data transmission channels, thusperforming multiple-channel parallel transmission.

In another aspect, the present invention provides a data transmissionapparatus comprising: information data entering means for enteringinformation data to memory means; data dividing means for dividing theinformation data entered into the memory means in sequence into aplurality of data segments, each having a predetermined time length, insuch a manner that the predetermined time length is increased insequence for each of the data segments until a predetermined time lengthis reached, and that, after the predetermined time length is reached,the length is fixed to the predetermined time length; packet dataforming means for obtaining continuous packet data by performing aspecific coding process on each of the plurality of data segments whichare formed in a divided manner by the data dividing means in order toform a plurality of continuous packet data; and data transmission meansfor transmitting each of the plurality of continuous packet dataobtained from the packet data forming means through individual datatransmission channels, thus performing multiple-channel paralleltransmission.

In another aspect, the present invention provides a data receivingmethod comprising the steps of: receiving a plurality of segmentedpacket data, which is obtained in such a manner that each of a pluralityof data segments having time lengths which are increased in sequenceuntil a predetermined time length is reached and which are fixed to thepredetermined time length after the predetermined time length is reachedis converted, each of the plurality of segmented packet data beingrepeatedly transmitted through individual data transmission channels;obtaining a plurality of data segments, each of which has apredetermined time length, on the basis of each of the plurality of thereceived segmented packet data; and sending the plurality of datasegments in sequence in order to reproduce the information data.

In another aspect, the present invention provides a data receivingmethod comprising the steps of: receiving a plurality of continuouspacket data, which is obtained in such a manner that a specific decodingprocess is performed on each of a plurality of data segments having timelengths which are increased in sequence until a predetermined timelength is reached and which are fixed to the predetermined time lengthafter the predetermined time length is reached, each of the continuouspacket data being repeatedly transmitted through individual datatransmission channels; obtaining a plurality of data segments, each ofwhich has a predetermined time length, by reproducing a data segment onthe basis of a portion of a predetermined amount of data in each of thereceived continuous packet data; and sending the plurality of datasegments in sequence in order to reproduce the information data.

In another aspect, the present invention provides a data receivingapparatus comprising: packet data entering means for receiving aplurality of segmented packet data, which is obtained in such a mannerthat each of a plurality of data segments having time lengths which areincreased in sequence until a predetermined time length is reached andwhich are fixed to the predetermined time length after the predeterminedtime length is reached is converted, each of the plurality of segmentedpacket data being repeatedly transmitted through individual datatransmission channels, and for entering the segmented packet data tomemory means; data segment forming means for obtaining a plurality ofdata segments, each of which has the predetermined time length, on thebasis of the plurality of segmented packet data entered into the memorymeans; and data reproduction means for sending the plurality of datasegments obtained by the data segment forming means in sequence in orderto reproduce the information data.

In another aspect, the present invention provides a data receivingapparatus comprising: packet data entering means for receiving aplurality of continuous packet data, which is obtained in such a mannerthat a specific decoding process is performed on each of a plurality ofdata segments having time lengths which are increased in sequence untila predetermined time length is reached and which are fixed to thepredetermined time length after the predetermined time length isreached, each of the plurality of continuous packet data beingrepeatedly transmitted through individual data transmission channels,and for entering the continuous packet data to memory means; datasegment forming means for obtaining a plurality of data segments eachhaving the predetermined time length on the basis of a portion of apredetermined amount of data in each a plurality of continuous packetdata entered into the memory means; and data reproduction means forsending the plurality of data segments obtained by the data segmentforming means in sequence in order to reproduce the information data.

In the data transmission method and the data transmission apparatusaccording to the present invention, when information data to betransmitted is divided into a plurality of data segments, the timelength of each data segment is increased in sequence until apredetermined time length is reached, and after the predetermined timelength is reached, the time length of each data segment is fixed to thepredetermined time length. Consequently, the corresponding time lengthsof a plurality of segmented packet data which is repeatedly transmittedthrough a plurality of data transmission channels, respectively, areincreased in sequence until a predetermined time length is reached, andare fixed to the predetermined time length after the predetermined timelength is reached.

As a result, on the receiving side which receives a series of segmentedpacket data, which reproduces the series of segmented packet data, andwhich obtains the original information data, the time required from whenthe reproduction of the first segment of the series of data segments isstarted until the last segment is reproduced becomes longer than that ina case where the corresponding time lengths of a plurality of datasegments formed as a result of information data being divided areincreased gradually from the first data segment to the last datasegment. Furthermore, since the point in time when the reproduction ofthe last data segment of the series of data segments is started is aninvariable time which is determined in such a manner as to correspond tothe end point of the information data which is divided into a pluralityof data segments, the point in time at which the reproduction of thefirst data segment of the series of data segments should be started onthe received side is set as a point in time earlier than that in a casewhere the corresponding time lengths of a plurality of data segmentsformed as a result of information data being divided are increasedgradually from the first data segment to the last data segment.

Therefore, in a case where, for example, content to be transmitted islive content, information data (live information data) representing thelive content is divided into a plurality of data segments, and therepeated transmission of each of the plurality of the segmented packetdata based on each of the plurality of data segments through individualdata transmission channels is started in sequence according to a statein which the live information data arrives, a reproduction start waitingtime associated with the reproduction of the live information data onthe received side can be reduced.

Furthermore, in the data transmission method and the data transmissionapparatus according to the present invention, when information data tobe transmitted is divided into a plurality of data segments, the timelength of each data segment is increased in sequence until apredetermined time length is reached, and after the predetermined timelength is reached, the time length of each data segment is fixed to thepredetermined time length. Consequently, the time length of a portion ofa predetermined amount of data in each of a plurality of continuouspacket data which is transmitted through a plurality of datatransmission channels, respectively, is increased in sequence until apredetermined time length is reached, and is fixed to the predeterminedtime length after the predetermined time length is reached.

As a result, on the receiving side which receives a portion of apredetermined amount of data in each of a plurality of continuous packetdata, which reproduces a series of data segments, and which obtains theoriginal information data, the time required from when the reproductionof the first segment of the series of data segments is started until thelast segment is reproduced becomes longer than that in a case where thecorresponding time lengths of the plurality of data segments formed as aresult of information data being divided are increased gradually fromthe first data segment to the last data segment. Furthermore, since thepoint in time at which the reproduction of the last data segment of theseries of data segments is started is a point in time at which a timecorresponding to the time length of a portion of a predetermined amountof data in the continuous packet data corresponding to the last segmentof the series of data segments has passed from the end point in time ofthe information data which is divided into a plurality of data segments,the point in time at which the reproduction of the first data segment ofthe series of data segments should be started on the received side isset as a point in time earlier than that in a case where thecorresponding time lengths of the plurality of data segments formed as aresult of information data being divided are increased gradually fromthe first data segment to the last data segment.

Therefore, in a case where, for example, content to be transmitted islive content, information data (live information data) representing thelive content is divided into a plurality of data segments, and thetransmission each of a plurality of continuous packet data based on eachof the plurality of data segments through individual data transmissionchannels is started in sequence according to a state in which the liveinformation data arrives, a reproduction start waiting time associatedwith the reproduction of the live information data on the receiving sidecan be reduced.

In the data receiving method and the data receiving apparatus accordingto the present invention, a plurality of segmented packet data, which isrepeatedly transmitted by the data transmission apparatus for use withthe data transmission method according to the present invention, isreceived. Then, on the basis of the plurality of the received segmentedpacket data, data segments having time lengths which are increased insequence until a predetermined time length is reached and which arefixed to the predetermined time length after the predetermined timelength is reached are obtained in sequence. The data segments are sentin sequence, and the original information data is reproduced.

Furthermore, in the data receiving method and the data receivingapparatus according to the present invention, a portion of apredetermined amount of data in each of a plurality of continuous packetdata, which is transmitted by the data transmission apparatus for usewith the data transmission method according to the present invention, isreceived. Then, on the basis of the portion of the predetermined amountof data in each of the plurality of the received continuous packet data,data segments having time lengths which are increased in sequence untila predetermined time length is reached and which are fixed to thepredetermined time length after the predetermined time length is reachedare obtained in sequence. The data segments are sent in sequence, andthe original information data is reproduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block connection diagram showing an example of a datatransmission apparatus according to the present invention for use withan example of a data transmission method according to the presentinvention;

FIG. 2 is a timing chart illustrating the operation of a transmissionserver in the example shown in FIG. 1;

FIG. 3 is a flowchart showing an example of a program executed by a CPUincorporated in the transmission server in the example shown in FIG. 1when the CPU performs operation control;

FIG. 4 is a flowchart showing an example of a program executed by theCPU incorporated in the transmission server in the example shown in FIG.1 when the CPU performs operation control;

FIG. 5 is a timing chart illustrating the operation of the transmissionserver in the example shown in FIG. 1;

FIG. 6 is a flowchart showing an example of a program executed by theCPU incorporated in the transmission server in the example shown in FIG.1 when the CPU performs operation control;

FIG. 7 is a block connection diagram showing an example of a datareceiving apparatus according to the present invention for use with anexample of a data receiving method according to the present invention;

FIG. 8 is a timing chart illustrating the operation of a receivingserver in the example shown in FIG. 7;

FIG. 9 is a flowchart showing an example of a program executed by a CPUincorporated in the receiving server in the example shown in FIG. 7 whenthe CPU performs operation control;

FIG. 10 is a timing chart illustrating the operation of the receivingserver in the example shown in FIG. 7;

FIG. 11 is a flowchart showing an example of a program executed by theCPU incorporated in the receiving server in the example shown in FIG. 7when the CPU performs operation control;

FIG. 12 is a timing chart illustrating data transmission of an on-demandform in which an equal-length division technique and a repeatedtransmission technique are used;

FIG. 13 is a timing chart illustrating data transmission of an on-demandform in which an equal-length division technique and a continuoustransmission technique are used;

FIG. 14 is a timing chart illustrating data transmission of an on-demandform in which an unequal-length division technique and a repeatedtransmission technique are used;

FIG. 15 is a timing chart illustrating data transmission of an on-demandform in which an unequal-length division technique and a continuoustransmission technique are used;

FIG. 16 is a timing chart showing an example of data transmission of anon-demand form in which content to be transmitted is live informationand in which an unequal-length division technique and a repeatedtransmission technique are used; and

FIG. 17 is a timing chart illustrating data transmission of an on-demandform in which content to be transmitted is live information and in whichan unequal-length division technique and a continuous transmissiontechnique are used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an example of a data transmission apparatus according tothe present invention for use with an example of a data transmissionmethod according to the present invention.

In the example shown in FIG. 1, a video camera 11 is provided. The videocamera 11 captures an image and collects sound of a live performance ofa piece of music, forms a camera output signal DCM containing videoinformation and audio information in such a manner as to represent liveinformation, and supplies the signal to an encoder 12. The encoder 12performs a compression coding process in compliance with a specificmethod on the camera output signal DCM representing the liveinformation, and forms, as information data, encoded data DECrepresenting live content based on the live performance of a piece ofmusic. The specific method for the compression coding process used forsuch a case is, for example, a standard method called MPEG (MovingPicture Experts Group), which has been developed by MPEG, a task forceof a technical committee in the international standardizationorganization, and which is approved as a standard.

The encoded data DEC obtained from the encoder 12 is supplied to atransmission server 13. The transmission server 13 has a basicconfiguration such that an input interface (input I/F) 15, a centralprocessing unit (CPU) 16, a program memory section 17, a data memorysection 18 formed by a hard disk drive (HDD), and an output interface(output I/F) 19 are connected to a data bus 14.

In the transmission server 13, the encoded data DEC supplied through theinput I/F 15 is processed in sequence in accordance with an operationprogram stored in the program memory section 17 under the operationcontrol of the CPU 16. First, the encoded data DEC is temporarilyentered into the data memory section 18. Then, the encoded data DEC,such as that shown in the timing chart in FIG. 2, which is temporarilyentered into the data memory section 18, is divided into a plurality ofdata segments DS1 to DSn, as shown in FIG. 2.

In such a case, the data segments DS1 to DSn are formed in such a mannerthat the first data segment DS1 has a relatively short time length Ta,the data segments DS2 to DS5 which follow the data segment DS1 havegradually increasing time lengths Tb to Te (Ta<Tb<Tc<Td<Te) (graduallyincreasing segment lengths), and the data segments DS6 to DSn whichfollow the data segment DS5 each have a fixed time length Te (equalsegment length) equal to the time length Te of the data segment DS5.That is, each of the data segments DS1 to DSn has a predetermined timelength, the predetermined time lengths of the data segments DS1 to DS5are made to be time lengths which increase in sequence until apredetermined time length Te is reached, and the time length of each ofthe data segments DS6 to DSn after that is made to be a predeterminedtime length Te equal to that of the data segment DS5.

As a result, segmented data composed of the data segments DS1 to DSn isobtained. As shown in FIG. 2, the beginning of this segmented data ismade to be a live information start point in synchronization with thebeginning of the encoded data DEC, and the end thereof is synchronizedwith the end of the encoded data DEC. In a state in which the segmenteddata composed of the data segments DS1 to DSn is obtained in thismanner, the CPU 16 transmits each of the data segments DS1 to DSn.

In a first mode of transmission of each of the data segments DS1 to DSn,performed by the CPU 16, the CPU 16 converts the data segments DS1 toDSn in sequence into a plurality of segmented packet data DP1 to DPn.Each of the segmented packet data DP1 to DPn is made to be packet streamdata on which a predetermined coding process is performed.

Each of the segmented packet data DP1 to DPn has a predetermined timelength, the predetermined time lengths of the segmented packet data DP1to DP5 are made to be time lengths which increase in sequence until thepredetermined time length Te is reached, and the predetermined timelength of each of the segmented packet data DP6 to DPn is made to have apredetermined time length Te equal to that of the segmented packet dataDP5.

Then, as the segmented packet data DP1 to DPn is formed in sequence onthe basis of the data segments DS1 to DSn, the segmented packet data DP1to DPn is sent to a network connected to the transmission server 13through an output I/F 19 so that the segmented packet data DP1 to DPn isrepeatedly transmitted through the data transmission channels CH1 toCHn, respectively.

In such a case, as shown in FIG. 2, first, repeated transmission of thesegmented packet data DP1 based on the data segment DS1 through the datatransmission channel CH1 is started from the live information startpoint which is the beginning of the data segment DS1. Then, repeatedtransmission of the segmented packet data DP2 based on the data segmentDS2 through the data transmission channel CH2 is started from the pointin time, which is the beginning of the data segment DS2. Hereafter, in asimilar manner, repeated transmission of the segmented packet data DP3to DPn based on the data segments DS3 to DSn through the datatransmission channels CH3 to CHn, respectively, is started in sequencefrom the point in time, which is the beginning of each of the datasegments DS3 to DSn.

As a result, the segmented packet data DP1 to DPn is repeatedlytransmitted through the data transmission channels CH1 to CHn,respectively, and thus, n-channel parallel transmission is performed. Inthis manner, the segmented packet data DP1 to DPn which is repeatedlytransmitted through the output I/F 19 forms transmission data DT of nchannels.

FIG. 3 is a flowchart showing an example of an operation programexecuted by the CPU 16 when the encoded data DEC, which is informationdata, is divided into data segments DS1 to DSn. In the operation programrepresented by this flowchart shown in FIG. 3, after the start, in step21, a variable N is initialized to “1”.

Next, in step 22, entry of the encoded data DEC, which is informationdata, into the data memory section (HDD) 18 is started. In thesubsequent step 23, formation of the N-th (Ns=N) data segment DSN basedon the encoded data DEC entered into the data memory section 18 and thestorage into the data memory section (HDD) 18 are started, and then theprocess proceeds to step 24.

In step 24, it is determined whether or not the storage of the datasegment DSN of Ns=N in the data memory section (HDD) 18 is completed.When the storage is not completed, the determination in step 24 isrepeated. When the storage is completed, in step 25, the variable N isincreased by “1”, and then the process proceeds to step 26. In step 26,it is determined whether or not the variable N has reached n+1. When thevariable N has not reached n+1, the process returns to step 23, wherethis and subsequent steps are repeated. When the variable N has reachedn+1, the program is terminated.

Under such a state, in step 23 in which the data segment DSN of Ns=N isformed, the data segments DS1 to DS5 having time lengths which increasein sequence until a predetermined time length is reached, and the datasegments DS6 to DSn each having a predetermined time length equal tothat of the data segment DS5 are formed.

FIG. 4 is a flowchart showing an example of an operation programexecuted by the CPU 16 when the data segments DS1 to DSn are convertedinto the segmented packet data DP1 to DPn, respectively, and when theobtained segmented packet data DP1 to DPn is repeatedly transmittedthrough the data transmission channels CH1 to CHn, respectively. In theoperation program represented by this flowchart shown in FIG. 4, afterthe start, in step 31, the variables N and M are each initialized to“1”.

Next, in step 32, it is determined whether or not the storage of thedata segment DSN of Ns=N into the data memory section (HDD) 18 isstarted. When the determination result shows that the storage of thedata segment DSN of Ns=N into the data memory section 18 is not started,the determination in step 32 is repeated. When the storage of the datasegment DSN of Ns=N into the data memory section 18 is started, in step33, the data segment DSN of Ns=N is read from the data memory section 18and is converted into segmented packet data DPN, which is packet streamdata, on which a predetermined coding process is performed.

Then, in step 34, the repeated transmission of the segmented packet dataDPN, obtained in step 33, through a data transmission channel M (CHM) isstarted.

Thereafter, in step 35, the variables N and M are each increased by “1”,and then the process proceeds to step 36. In step 36, it is determinedwhether or not each of the variables N and M has reached n+1. If each ofthe variables N and M has not reached n+1, the process returns to step32, where this and subsequent steps are repeated. If each of thevariables N and M has reached n+1, the program is terminated.

In such a state, in step 33 in which the data segment DSN of Ns=N isconverted into segmented packet data DPN, the segmented packet data DP1to DP5 having time lengths which increase in sequence until apredetermined time length is reached, and the segmented packet data DP6to DPn each having a predetermined time length equal to that of thesegmented packet data DP5 are formed.

In the manner described above, in the example shown in FIG. 1, in thefirst mode of transmission of each of the data segments DS1 to DSn,performed by the CPU 16, the encoded data DEC representing live contentwhich is information data to be transmitted is divided into the datasegments DS1 to DSn such that the data segments DS1 to DS5 have timelengths which increase in sequence until a predetermined time length isreached and the data segments DS6 to DSn following that have a fixedtime length equal to that of the data segment DS5. The data segments DS1to DSn are converted into segmented packet data DP1 to DPn,respectively, and are repeatedly transmitted through the datatransmission channels CH1 to CHn, respectively. At this time, repeatedtransmission of each of the segmented packet data DP1 to DPn is startedin sequence according to a state in which the encoded data DEC arrivesin the transmission server 13. As a result, on the receiving side whichreceives a series of segmented packet data DP1 to DPn in order to obtaina series of data segments DS1 to DSn and which reproduces the originalencoded data DEC, a reproduction start waiting time associated with thereproduction of the encoded data DEC is reduced.

Furthermore, in a second mode of transmission of each of the datasegments DS1 to DSn, performed by the CPU 16, the CPU 16 converts thedata segments DS1 to DSn in sequence into a plurality of continuouspacket data DLT1 to DLTn, respectively, and continuously transmits thedata through the data transmission channels CH1 to CHn, respectively.

The continuous packet data DLT1 is formed by a nearly infinitecontinuous packet stream, obtained by performing a specific codingprocess, which is the above-described LT coding process, on the datasegment DS1. Such a packet stream is formed so as to be capable ofreproducing the original data segment DS1 from one of the portionshaving a predetermined amount of data corresponding to approximately105% of the data segment DS1 within that packet stream. The portionhaving the predetermined amount of data has a time length correspondingto the time length of the data segment DS1.

Similarly to the continuous packet data DLT1, each of the continuouspacket data DLT2 to DLTn is also formed by a nearly infinite continuouspacket stream, obtained by performing a specific coding process, whichis the above-described LT coding process, on the data segments DS2 toDSn, respectively. Each of these packet streams is formed so as to becapable of reproducing one of the original data segments DS2 to DSn fromone of the portions having a predetermined amount of data correspondingto approximately 105% of one of the data segments DS2 to DSn within thatpacket stream. Such portions having the predetermined amount of datahave time lengths corresponding to the time lengths of the data segmentsDS2 to DSn, respectively.

Then, the continuous packet data DLT1 to DLTn are sent to a networkconnected to the transmission server 13 through the output I/F 19 sothat the continuous packet data DLT1 to DLTn are transmitted through thedata transmission channels CH1 to CHn, respectively.

In such a case, for example, as shown in FIG. 5, the CPU 16 first startsthe conversion of the data segment DS1 into the continuous packet dataDLT1 and the transmission thereof through the data transmission channelCH1 when the formation of the data segment DS1 is completed. Then, theconversion of the data segment DS2 into the continuous packet data DLT2and the transmission thereof through the data transmission channel CH2are started when the formation of the data segment DS2 is completed.Hereafter, in a similar manner, the conversion of each of the datasegments DS3 to DSn into each of the continuous packet data DLT3 to DLTnand the transmission thereof through each of the data transmissionchannels CH3 to CHn are started in sequence when the formation of eachof the data segments DS3 to DSn is completed.

As a result, the continuous packet data DLT1 to DLTn is transmittedthrough the data transmission channels CH1 to CHn, respectively, andthus, n-channel parallel transmission is performed. In this manner, thecontinuous packet data DLT1 to DLTn which is repeatedly transmittedthrough the output I/F 19 forms transmission data DT of n channels.

FIG. 6 is a flowchart showing an example of an operation programperformed by the CPU 16 when the CPU 16 converts data segments DS1 toDSn into continuous packet data DLT1 to DLTn, respectively, andtransmits the obtained continuous packet data DLT1 to DLTn through thedata transmission channels CH1 to CHn, respectively.

In the operation program represented by this flowchart shown in FIG. 6,after the start, in step 41, the variables N and M are each initializedto “1”.

Next, in step 42, it is determined whether or not the storage of thedata segments DSN of Ns=N into the data memory section (HDD) 18 iscompleted. When the determination result shows that the storage of thedata segment DSN of Ns=N into the data memory section 18 is notcompleted, the determination in step 42 is repeated. When the storage ofthe data segment DSN of Ns=N into the data memory section 18 iscompleted, in step 43, the data segment DSN of Ns=N is read from thedata memory section 18, and a conversion into continuous packet dataDLTN, formed of a nearly infinite continuous packet stream, obtained byperforming a specific coding process thereon, is started. In thesubsequent step 44, transmission of the continuous packet data DLTNwhose conversion is started through the data transmission channel M(CHM) is started.

Thereafter, in step 45, the variables N and M are each increased by “1”,and then the process proceeds to step 46. In step 46, it is determinedwhether or not each of the variables N and M has reached n+1. If each ofthe variables N and M has not reached n+1, the process returns to step42, where this and subsequent steps are repeated. If each of thevariables N and M has reached n+1, the program is terminated.

In the manner described above, in the example shown in FIG. 1, also, ina second mode of transmission of each of the data segments DS1 to DSn,performed by the CPU 16, the encoded data DEC representing content whichis information data to be transmitted is divided into data segments DS1to DSn such that the data segments DS1 to DS5 have time lengths whichare increased in sequence until a predetermined time length is reachedand such that the data segments DS6 to DSn after that have a fixed timelength equal to that of the data segment DS5, the data segments DS1 toDSn are converted into continuous packet data DLT1 to DLTn,respectively, and the data is transmitted through the data transmissionchannels CH1 to CHn. In this case, the transmission of each of thecontinuous packet data DLT1 to DLTn is started in sequence according toa state in which the encoded data DEC arrives in the transmission server13. As a result, on the receiving side which receives a portion of apredetermined amount of data in each of a series of continuous packetdata DLT1 to DLTn in order to obtain a series of data segments DS1 toDSn and which reproduces the original encoded data DEC, a reproductionstart waiting time associated with the reproduction of the encoded dataDEC is reduced.

FIG. 7 shows an example of a data receiving apparatus according to thepresent invention for use with an example of a data receiving methodaccording to the present invention.

In the example shown in FIG. 7, a receiving server 51 for receivingtransmission data DT sent in the example shown in FIG. 1 is provided.The receiving server 51 has a basic configuration such that an inputinterface (input I/F) 53, a central processing unit (CPU) 54, a programmemory section 55, a data memory section 56 formed by a hard disk drive(HDD), and an output interface (output I/F) 57 are connected to a databus 52.

In a case where, as shown in FIG. 2, the transmission data DT sent inthe example shown in FIG. 1 is such that the segmented packet data DP1to DPn is repeatedly transmitted through the data transmission channelsCH1 to CHn, respectively, in the receiving server 51, as shown in thetiming chart in FIG. 8, each of the segmented packet data DP1 to DPn,supplied through the input I/F 53, which is repeatedly transmittedthrough the data transmission channels CH1 to CHn, is processed insequence in accordance with an operation program stored in the programmemory section 55 under the operation control of the CPU 54. First, thesegmented packet data DP1 to DPn which is repeatedly transmitted throughthe data transmission channels CH1 to CHn is received and is temporarilyentered into the data memory section (HDD) 56.

In such a case, according to the starting sequence of the repeatedtransmission of each of the segmented packet data DP1 to DPn in theexample shown in FIG. 1, first, the time, shown in FIG. 8, correspondingto the beginning of the segmented data supplied in the example of FIG.1, that is, at time ta corresponding to the transmission starting timeof the segmented packet data DP1, entry of the segmented packet data DP1into the data memory section 56 is started. Thereafter, at a timecorresponding to the transmission starting time of each of the segmentedpacket data DP2 to DPn, entry of the segmented packet data DP2 to DPninto the data memory section 56 is started in sequence.

In such a situation, operations such as those shown in FIG. 8 arestarted. That is, at time tb in which a reproduction start waiting timeTv′ which is set in advance has passed from time ta, the segmentedpacket data DP1 entered into the data memory section 56 is read from thedata memory section 56. By performing a predetermined decoding processon packet stream data, which forms the packet data, on which apredetermined coding process is performed, a data segment DS1 isobtained. Subsequently, each of the segmented packet data DP2 to DPnentered into the data memory section 56 is read from the data memorysection 56. By performing a predetermined decoding process on the packetstream data, which forms the segmented packet data, on which apredetermined coding process is performed, data segments DS2 to DSn arecontinuously obtained in sequence.

The data segments DS1 to DSn which are continuously obtained in sequenceby the operations which are started in this manner are sent in sequence,and the original encoded data DEC representing live content isreproduced.

In the manner described above, as a result of starting an operation forobtaining the data segment DS1 at time tb when a preset reproductionstart waiting time Tv′ has passed from time ta, an operation forobtaining the data segment DSn based on the first data of the segmentedpacket data DPn which is repeatedly transmitted, which is entered intothe data memory section 56 at time tc shown in FIG. 8 can be started attime td when the entry of the segmented packet data DPn into the datamemory section 56 is completed. The time td corresponds to the end ofthe segmented data in the example shown in FIG. 1, that is, the time ofthe end of the data segment DSn.

More specifically, the reproduction start waiting time Tv′ is set inadvance so that, at time tb, an operation for obtaining the data segmentDS1 is started to obtain the data segments DS1 to DSn−1 in sequence,thereafter, at time td, an operation for obtaining the data segment DSnbased on the first data of the segmented packet data DPn which isrepeatedly transmitted can be started, making it possible tocontinuously obtain the data segments DS1 to DSn. Such a reproductionstart waiting time Tv′ is computed as a time from time ta correspondingto the beginning of the segmented data supplied in the example shown inFIG. 1 up to the computed time tb, which is earlier by an amount of timerequired to continuously obtain the data segments DS1 to DSn−1 than timetd corresponding to the end of the segmented data supplied in theexample shown in FIG. 1.

The reproduction start waiting time Tv′ is reduced in comparison withthe reproduction start waiting time Tv in a case where the data segmentsDS1 to DSn which form the encoded data DEC to be reproduced are formedsuch that the data segments DS1 to DS5 among them have time lengthswhich are increased in sequence until a predetermined time length isreached and the data segments DS6 to DSn after that each have a fixedtime length equal to that of the data segment DS5, and as a result, forexample, as shown in FIG. 16, the corresponding time lengths of the datasegments DS1 to DSr which forms the encoded data to be reproduced areincreased gradually from the first segment to the last segment.

FIG. 9 is a flowchart showing an example of an operation programexecuted by the CPU 54 in the receiving server 51 when the CPU 54 entersthe segmented packet data DP1 to DPn which form the transmission data DTof n channels into the data memory section (HDD) 56, converts thesegmented packet data DP1 to DPn into data segments DS1 to DSn,respectively, and reproduces the encoded data DEC. In the operationprogram represented by this flowchart shown in FIG. 9, after the start,in step 61, the variable N is initialized to “1”.

Next, in step 62, entry of the segmented packet data DP1 to DPn,supplied through the input I/F 53, which forms the transmission data DTof n channels and which is repeatedly transmitted through the datatransmission channels CH1 to CHn, into the data memory section 56 isstarted.

Then, in step 63, it is determined whether or not the segmented packetdata DPN of Ns=N is entered into the data memory section 56. When thedetermination result shows that the segmented packet data DPN is notentered into the data memory section 56, the determination in step 63 isrepeated. When the segmented packet data DPN is entered into the datamemory section 56, in step 64, the segmented packet data DPN is readfrom the data memory section 56, a predetermined decoding process isperformed on the packet stream data, which forms the segmented packetdata DPN, on which a predetermined coding process is performed, in orderto reproduce the data segment DSN from the segmented packet data DPN,and the obtained data segment DSN is sent.

Thereafter, in step 65, the variable N is increased by “1”, and then theprocess proceeds to step 66. In step 66, it is determined whether or notthe variable N has reached n+1. When the variable N has not reached n+1,the process returns to step 63, where this and subsequent steps arerepeated. When the variable N has reached n+1, the program isterminated.

Furthermore, in a case where the transmission data DT sent in theexample shown in FIG. 1 is formed in such a way that, as shown in FIG.5, the continuous packet data DLT1 to DLTn is transmitted through thedata transmission channels CH1 to CHn, respectively, in the receivingserver 51, as shown in the timing chart in FIG. 10, each of thecontinuous packet data DLT1 to DLTn, supplied through the input I/F 53,which is transmitted through the data transmission channels CH1 to CHn,is processed in sequence in accordance with the operation program storedin the program memory section 55 under the operation control of the CPU54. First, the continuous packet data DLT1 to DLTn which is transmittedthrough the data transmission channels CH1 to CHn is received and istemporarily entered into the data memory section (HDD) 56.

In such a case, according to the starting sequence of the transmissionof each of the continuous packet data DLT1 to DLTn in the example shownin FIG. 1, first, at a time in which a time until the formation of thedata segment DS1 is completed has passed from time te corresponding tothe beginning of the segmented data supplied in the example of FIG. 1,that is, at the time corresponding to the transmission starting time ofthe continuous packet data DLT1, entry of the continuous packet dataDLT1 into the data memory section 56 is started. Thereafter, at a timecorresponding to each of the transmission starting points of each of thecontinuous packet data DLT1 to DLTn, entry of the continuous packet dataDLT2 to DLTn into the data memory section 56 is started in sequence.

In such a situation, operations such as those shown in FIG. 10 arestarted. That is, at time tf in which the reproduction start waitingtime Tw′ which is set in advance has passed from time te, a portion of apredetermined amount of data in the continuous packet data DLT1 enteredinto the data memory section 56 is read from the data memory section 56.By performing a specific decoding process on packet stream data, whichforms the data, on which a specific coding process is performed, thedata segment DS1 is obtained. Subsequently, each of the continuouspacket data DLT2 to DLTn entered into the data memory section 56 is readfrom the data memory section 56, and by performing a specific decodingprocess on packet stream data, which forms the continuous packet data,on which a specific coding process is performed, the data segments DS2to DSn are continuously obtained in sequence.

The data segments DS1 to DSn which are continuously obtained in sequenceaccording to the operations which are started in this manner are sent insequence, and the original encoded data DEC representing live content isreproduced.

As described above, as a result of starting an operation for obtainingthe data segment DS1 at time tf when a preset reproduction start waitingtime Tw′ has passed from time te, an operation for obtaining the datasegment DSn based on the portion of the predetermined amount of data ofthe continuous packet data DLTn, which is obtained first, which isentered into the data memory section 56 at time tg shown in FIG. 10 canbe started at time th when the entry of the portion of the predeterminedamount of data in the continuous packet data DLTn into the data memorysection 56 is completed. The time th is a time when a time correspondingto the time length of the portion of the predetermined amount of data ofthe continuous packet data DLTn, which is obtained first, has passedfrom the end of the segmented data supplied in the example shown in FIG.1, that is, time tg of the end of the segmented data DSn.

More specifically, the reproduction start waiting time Tw′ is set inadvance so that, at time tf, as a result of starting an operation forobtaining the data segment DS1, the data segments DS1 to DSn−1 areobtained in sequence, thereafter, at time th, an operation for obtainingthe data segment DSn based on the first portion of the predeterminedamount of data of the continuous packet data DLTn which is transmittedcan be started, making it possible to continuously obtain the datasegments DS1 to DSn. Such a reproduction start waiting time Tw′ iscomputed as a time from time te corresponding to the beginning of thesegmented data supplied in the example shown in FIG. 1 up to thecomputed time tf, which is earlier by an amount of time required tocontinuously obtain the data segments DS1 to DSn−1 than time th in whichthe time corresponding to the time length of the portion of thepredetermined amount of data of continuous packet data DLTn, which isobtained first, has passed from time tg corresponding to the end of thesegmented data supplied in the example shown in FIG. 1.

Furthermore, the data segments DS1 to DSn which form the encoded dataDEC to be reproduced are formed such that the data segments DS1 to DS5among them have time lengths which are increased in sequence until apredetermined time length is reached and the data segments DS6 to DSnafter that have time lengths equal to that of the data segment DS5. As aresult, the reproduction start waiting time Tw′ is reduced in comparisonwith the reproduction start waiting time Tw in a case where, forexample, as shown in FIG. 17, the corresponding time lengths of the datasegments DS1 to DSr which form the encoded data to be reproduced areincreased gradually from the first segment to the last segment.

FIG. 11 is a flowchart showing an example of an operation programexecuted by the CPU 54 in the receiving server 51 in a case where theCPU 54 enters the continuous packet data DLT1 to DLTn which forms thetransmission data DT of n channels into the data memory section (HDD)56, which obtains the data segments DS1 to DSn based on a portion of apredetermined amount of data in each of the continuous packet data DLT1to DLTn, and which reproduces the encoded data DEC. In the operationprogram represented by this flowchart shown in FIG. 11, after the start,in step 71, a variable N is initialized to “1”.

Next, in step 72, entry of the continuous packet data DLT1 to DLTn,which forms the transmission data DT of n channels, supplied through theinput I/F 53, which is transmitted through the data transmissionchannels CH1 to CHn, into the data memory section 56 is started.

In the subsequent step 73, it is determined whether or not a portion ofa predetermined amount of data in the continuous packet data DLTN ofNs=N is entered into the data memory section 56. When the determinationresult shows that a portion of a predetermined amount of data in thecontinuous packet data DLTN is not entered into the data memory section56, the determination in step 73 is repeated. When a portion of apredetermined amount of data in the continuous packet data DLTN isentered into the data memory section 56, in step 74, the portion of thepredetermined amount of data in the continuous packet data DLTN is readfrom the data memory section 56. A specific decoding process isperformed on the packet stream data, which forms the portion of thepredetermined amount of data in the continuous packet data DLTN, onwhich a specific coding process is performed, in order to reproduce thedata segment DS from the portion of the predetermined amount of data inthe continuous packet data DLTN, and the obtained data segment DSN issent.

Thereafter, in step 75, the variable N is increased by “1”, and then theprocess proceeds to step 76. In step 76, it is determined whether or notthe variable N has reached n+1. If the variable N has not reached n+1,the process returns to step 73, where this and subsequent steps arerepeated. When the variable N has reached n+1, the program isterminated.

In the manner described above, in the receiving server 51 in the exampleshown in FIG. 7, the encoded data DEC reproduced by the built-in CPU 54is sent from the receiving server 51 through the output I/F 57 and issupplied to a decoder 58. In the decoder 58, a decompression decodingprocess in compliance with a specific method is performed on the encodeddata DEC in order to obtain a reproduction output signal SVA containinga video information signal and an audio information signal, and thesignal is supplied to an audio/video monitor 59, whereby audio and videobased on the reproduction output signal SVA are produced.

1. A data transmission method comprising the steps of: dividinginformation data in sequence into a plurality of data segments, eachhaving a predetermined time length, in such a manner that saidpredetermined time length is increased in sequence for each of said datasegments until a predetermined time length is reached, and that, aftersaid predetermined time length is reached, the length is fixed to thepredetermined time length; converting each of the plurality of datasegments which are formed in a divided manner into segmented packet datain order to form a plurality of segmented packet data; and repeatedlytransmitting each of the plurality of segmented packet data throughindividual data transmission channels, thus performing multiple-channelparallel transmission.
 2. A data transmission method according to claim1, wherein the information data is subjected to a compression codingprocess.
 3. A data transmission method according to claim 1, wherein theinformation data is live information data, and repeated transmission ofeach of a plurality of segmented packet data through individual datatransmission channels is started in sequence according to a state inwhich said live information data arrives.
 4. A data transmission methodaccording to claim 1, wherein each of the plurality of segmented packetdata is obtained as packet stream data on which a predetermined codingprocess is performed.
 5. A data transmission method comprising the stepsof: dividing information data in sequence into a plurality of datasegments, each having a predetermined time length, in such a manner thatsaid predetermined time length is increased in sequence for each of saiddata segments until a predetermined time length is reached, and that,after said predetermined time length is reached, the length is fixed tothe predetermined time length; obtaining continuous packet data byperforming a specific coding process on each of the plurality of datasegments which are formed in a divided manner in order to form aplurality of continuous packet data; and repeatedly transmitting each ofthe plurality of continuous packet data through individual datatransmission channels, thus performing multiple-channel paralleltransmission.
 6. A data transmission method according to claim 5,wherein the information data is subjected to a compression codingprocess.
 7. A data transmission method according to claim 5, wherein theinformation data is live information data, and transmission of each of aplurality of continuous packet data through individual data transmissionchannels is started in sequence according to a state in which said liveinformation data arrives.
 8. A data transmission apparatus comprising:information data entering means for entering information data to memorymeans; data dividing means for dividing the information data enteredinto said memory means in sequence into a plurality of data segments,each having a predetermined time length, in such a manner that saidpredetermined time length is increased in sequence for each of said datasegments until a predetermined time length is reached, and that, aftersaid predetermined time length is reached, the length is fixed to thepredetermined time length; packet data forming means for converting eachof the plurality of data segments which are formed in a divided mannerby the data dividing means into segmented packet data in order to obtaina plurality of segmented packet data; and data transmission means forrepeatedly transmitting each of the plurality of segmented packet dataobtained by the packet data forming means through individual datatransmission channels, thus performing multiple-channel paralleltransmission.
 9. A data transmission apparatus according to claim 8,further comprising data encoding means for supplying the informationdata on which a compression coding process is performed to theinformation data entering means.
 10. A data transmission apparatusaccording to claim 8, wherein the data transmission means starts insequence repeated transmission of each of the plurality of segmentedpacket data through individual data transmission channels according to astate in which the information data arrives at the information dataentering means.
 11. A data transmission apparatus according to claim 8,wherein the packet data forming means obtains each of the plurality ofsegmented packet data as packet stream data on which a predeterminedcoding process is performed.
 12. A data transmission apparatuscomprising: information data entering means for entering informationdata to memory means; data dividing means for dividing the informationdata entered into said memory means in sequence into a plurality of datasegments, each having a predetermined time length, in such a manner thatsaid predetermined time length is increased in sequence for each of saiddata segments until a predetermined time length is reached, and that,after said predetermined time length is reached, the length is fixed tothe predetermined time length; packet data forming means for obtainingcontinuous packet data by performing a specific coding process on eachof the plurality of data segments which are formed in a divided mannerby the data dividing means in order to form a plurality of continuouspacket data; and data transmission means for transmitting each of theplurality of continuous packet data obtained from the packet dataforming means through individual data transmission channels, thusperforming multiple-channel parallel transmission.
 13. A datatransmission apparatus according to claim 12, further comprising dataencoding means for supplying the information data on which a compressioncoding process is performed thereon to the data entering means.
 14. Adata transmission apparatus according to claim 12, wherein the datatransmission means starts in sequence transmission of each of theplurality of continuous packet data through individual data transmissionchannels according to a state in which the information data arrives atthe information data entering means.
 15. A data receiving methodcomprising the steps of: receiving a plurality of segmented packet data,which is obtained in such a manner that each of a plurality of datasegments having time lengths which are increased in sequence until apredetermined time length is reached and which are fixed to thepredetermined time length after the predetermined time length is reachedis converted, each of the plurality of segmented packet data beingrepeatedly transmitted through individual data transmission channels;obtaining a plurality of data segments, each of which has apredetermined time length, on the basis of each of the plurality of thereceived segmented packet data; and sending the plurality of datasegments in sequence in order to reproduce the information data.
 16. Adata receiving method according to claim 15, wherein the informationdata on which a compression coding process is performed is reproduced isperformed on the information data, and a decompression decoding processis performed on the information data.
 17. A data receiving methodaccording to claim 15, wherein a process for obtaining a data segmenthaving a predetermined time length on the basis of each of a pluralityof the received segmented packet data is started according to a state inwhich said plurality of segmented packet data arrives.
 18. A datareceiving method according to claim 15, wherein, by performing apredetermined decoding process on each of the plurality of the receivedsegmented packet data, a data segment having a predetermined time lengthis obtained.
 19. A data receiving method comprising the steps of:receiving a plurality of continuous packet data, which is obtained insuch a manner that a specific decoding process is performed on each of aplurality of data segments having time lengths which are increased insequence until a predetermined time length is reached and which arefixed to the predetermined time length after said predetermined timelength is reached, each of the continuous packet data being repeatedlytransmitted through individual data transmission channels; obtaining aplurality of data segments, each of which has a predetermined timelength, by reproducing a data segment on the basis of a portion of apredetermined amount of data in each of the received continuous packetdata; and sending the plurality of data segments in sequence in order toreproduce the information data.
 20. A data receiving method according toclaim 19, wherein the information data on which a compression codingprocess is performed is reproduced.
 21. A data receiving methodaccording to claim 19, wherein a process for reproducing a data segmenton the basis of each of the plurality of the received continuous packetdata is started according to a state in which said plurality ofcontinuous packet data arrives.
 22. A data receiving method according toclaim 19, wherein a data segment is reproduced by performing apredetermined decoding process on each of the plurality of the receivedcontinuous packet data.
 23. A data receiving apparatus comprising:packet data entering means for receiving a plurality of segmented packetdata, which is obtained in such a manner that each of a plurality ofdata segments having time lengths which are increased in sequence untila predetermined time length is reached and which are fixed to thepredetermined time length after said predetermined time length isreached is converted, each of the plurality of segmented packet databeing repeatedly transmitted through individual data transmissionchannels, and for entering the segmented packet data to memory means;data segment forming means for obtaining a plurality of data segments,each of which has said predetermined time length, on the basis of theplurality of segmented packet data entered into said memory means; anddata reproduction means for sending the plurality of data segmentsobtained by the data segment forming means in sequence in order toreproduce the information data.
 24. A data receiving apparatus accordingto claim 23, wherein said data reproduction means reproduces theinformation data on which a compression coding process is performed, andperforms a decompression decoding process on the information data.
 25. Adata receiving apparatus according to claim 23, wherein said datasegment forming means starts a process for obtaining a data segmenthaving a predetermined time length on the basis of each of the pluralityof received segmented packet data according to a state in which saidplurality of segmented packet data arrives at the packet data enteringmeans.
 26. A data receiving apparatus according to claim 23, whereinsaid data segment forming means obtains a data segment having apredetermined time length by performing a predetermined decoding processon each of the plurality of the received segmented packet data.
 27. Adata receiving apparatus comprising: packet data entering means forreceiving a plurality of continuous packet data, which is obtained insuch a manner that a specific decoding process is performed on each of aplurality of data segments having time lengths which are increased insequence until a predetermined time length is reached and which arefixed to the predetermined time length after said predetermined timelength is reached, each of the plurality of continuous packet data beingrepeatedly transmitted through individual data transmission channels,and for entering the continuous packet data to memory means; datasegment forming means for obtaining a plurality of data segments eachhaving said predetermined time length on the basis of a portion of apredetermined amount of data in each a plurality of continuous packetdata entered into said memory means; and data reproduction means forsending the plurality of data segments obtained by the data segmentforming means in sequence in order to reproduce the information data.28. A data receiving apparatus according to claim 27, wherein said datareproduction means reproduces the information data on which acompression coding process is performed, and performs a decompressiondecoding process on the information data.
 29. A data receiving apparatusaccording to claim 27, wherein said data segment forming means starts aprocess for reproducing a data segment on the basis of a portion of apredetermined amount of data in each of the plurality of the receivedcontinuous packet data according to a state in which said plurality ofcontinuous packet data arrives at the packet data entering means.
 30. Adata receiving apparatus according to claim 27, wherein said datasegment forming means performs a specific decoding process on a portionof a predetermined amount of data in each of the plurality of thereceived segmented packet data in order to reproduce a data segment.